How many pounds in a stone, and where did this measurement come from?

This might be helpful in finding out about the derivation of weights and measures.

The Babylonians used different stones for weighing different commodities. In modern English history, the same basis has been used for weight measurements. For the horseman, the "stone" weight was 14 pounds. In weighing wool the stone was 16 pounds. For the butcher and fishmonger, the stone was 8 pounds. The only legal stone weight in the imperial system was 14 pounds.

https://en.wikipedia.org/wiki/Stone_(unit)